Odometer is probably flashing because it was not the original... or perhaps the ECU was replaced. There is a programming feature where you can program the replacement odometer to sync with the ECU. However, the programming is restricted to the higher mileage from either the original or replacement odometer.
I believe the dash/odometer has it's own internal memory. If it is indeed a new odometer assembly, besides having to have it re-synced to the BCU, I would be just as concerned as to "why" it was replaced. It's also possible that the BCU got wet and that's what is causing the dis-connect. Re-sync again.
You also mention overheating. You'd better get this sorted first. Much more serious ramifications.
Other bugs? Fixer-uppers, Disco 2's are NOT!!